greglogan
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 posted on 24/3/08 at 01:05 AM |
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Build Your Own Exhaust Manifold
Hi guys
I was wondering if any of you guys had made your own manifold or know anything about it. I'm building a VFR800 engined Locost. The V4
arrangement is leaving me a little tight for space to get both sides mated together. I was think about making 2x 2into1 into 2 separate cans. Does
anyone know what affect this might have on engine performance?
If you have any other tips on building your own exhaust syatem, then please let me know.
Greg.
Women are meant to be loved, not understood.
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Ivan
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| posted on 24/3/08 at 07:21 AM |
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Unfortunately I have no idea whatsoever what effect a 2X2-1 would have compared to the original configuration but can suggest you look into similarly
configured bikes with same firing order and see if there are any and copy them.
I am pretty sure that the impact will be negative somewhere in the rev range and possibly positive somewhere else. 
One thing you could do would be to put a cross-connecting tube from the one manifold to the other to reduce negative impact.
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MR2
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| posted on 24/3/08 at 08:10 AM |
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I made two exhausts my self
'99 R1 engines. Cut the original exhaust runners about 4 cm from the EXUP cast and numbered the parts. then hang the EXUP part were you want it
and puzzle and cut the rest part til it fits. takes 3/6 cuts per runner to get it fitted. OK, maybe it doesnt have 100% flow, but I can always
buy/make a bigger better one after it been on the streets. Saw several 160 hp dyno sheets on R1 BEC's with welding bend exhausts with non lenght
matching runners.
I have twin engines that are packed in the back, so it would be expensive to have two made,( qouted 350 pounds a pop) and the needed the car for
measurements. Also I wanted to keep the exup system to test if it makes a difference, as most people just let the servo hang loose. EXUP cast also
makes it easy to mate the runners. On VFR 800 engine the exhaust is pretty difficult as it is made for two powerbands (vtec system) i wouls do some
measements on it.
i can mail some pictures, doesnt look that bad to me. weldit it with stainles mig/mag machine.
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greglogan
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| posted on 24/3/08 at 09:52 AM |
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Cheers guys
I started making one of the manifolds on Sat but couldn't believe the distortion created by welding. Once everything was welded and cooled, the
manifold had shrunk by over 1/2 inch. So was wondering was it worth the hassle.
Anyway, will try again. BTW, my VFR is 98 so is pre-VTEC. I'm gonna have a try again. It's gonna cost me about €60 at the most to
discover it doesn't work well, so it's worth a shot.
Pics to follow for comments/criticism...!
Greg.
Women are meant to be loved, not understood.
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mark chandler
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| posted on 24/3/08 at 12:37 PM |
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Distortion is a worry is you try and weld all the bits at one go, if you tack areas then backfill you can minimise this.
I found the best way was to linish the pipe ends so you get a really good fit, then hold together with masking tape on the joins.
You also need to think logically as some welds will be impossible if you assemble in the wrong order.
I made mine from stainless tube, cost ~£120 so well worth the effort.
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robertwa
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| posted on 24/3/08 at 04:30 PM |
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Hi Greg,
Take a look at TKS's photo archive on here, he has a similar setup
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